<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
   #d1{
     width: 100px;
     height: 100px;
     /*border: 10px double burlywood;*/
     border: 10px ridge brown;
     /*border: 10px inset burlywood;*/
     border-radius: 200px;
     text-align: center;
     line-height: 100px;
   }
   #d2{
     width: 100px;
     height: 100px;
     border:1px solid black;
   /*  添加内边距*/
     padding: 10px;
     padding-left:10px;
   /*  添加以下元素，内边距不在影响元素的宽高*/
     box-sizing:border-box;
   }
   body{
       margin: 0px;
   }
  </style>
</head>
<body>
  <div id="d1">边宽测试</div>
  <div id="d2">内边距</div>
</body>
</html>